Re-levelization: move non-docs content, rename content→docs

For better URLs, the content folder has been renamed 'docs' and all
other files have been moved up a level. Also, non-docs images have been
moved to the static folder at the top level where they belong.

Many relative paths had to be fixed to make this work.

@i18n/ja/docs/_snippets/interactive-tutorials/wait-step.md

@@ -0,0 +1,23 @@
+{% interactive-block label=default($label, "Wait") steps=$frontmatter.steps %}
+
+<table class="wait-step" data-explorerurl="https://testnet.xrpl.org">
+  <tr>
+    <th>トランザクションのID:</th>
+    <td class="waiting-for-tx">(無）</td>
+  <tr>
+    <th>最新の検証レジャーインデックス：</th>
+    <td class="validated-ledger-version">接続されていません</td>
+  </tr>
+  <tr>
+    <th>送信時のレジャーインデックス：</th>
+    <td class="earliest-ledger-version">（まだ送信されません）</td>
+  </tr>
+  <tr>
+    <th>トランザクションの<code>LastLedgerSequence</code>:</th>
+    <td class="lastledgersequence">(準備されません）</td>
+  </tr>
+  <tr class="tx-validation-status">
+  </tr>
+</table>
+
+{% /interactive-block %}